Carbonated beverages are commonly packaged in multiple serving containers of 1 liter or greater capacity. As servings are poured out of the container, the carbon dioxide in solution within the beverage, tends to escape into the space left between the liquid and the top of the container. Every time the container is unsealed to pour the next drink the carbon dioxide escapes into the air. After a few servings have been poured out of the container, the remainder of the beverage has lost most of its carbonation and turns flat A partial solution to this problem is provided by preventing the carbon dioxide which has gathered in the empty part of a partially drawn beverage container to escape. This can be achieved by replacing the cap of the container by a siphoning dispenser which uses the pressure created by the carbon dioxide in the top region of the container to push the liquid through a straw from the bottom of the container to a manually controllable valve in the dispensing cap. Such a device is disclosed in U.S. Pat. No. 4,860,932 Nagy. This type of carbonated drink dispensing device is effective so long as there is enough carbon dioxide to push the remaining liquid through the system. However, when the level of liquid drops within the bottle, some of the carbon dioxide escapes through the straw as the bottle is tipped. Moreover, as the liquid level drops, and the air gap expands, the carbon dioxide pressure is not enough to push the remainder of the liquid through the straw and out of the container.